The invention relates to an optical correlator which is able to work with incoherent light, particularly for use in real time image processing systems, which recognizes objects having particular shapes and sizes and determines their coordinates.
It is known that the cross correlation algorithm of images having specified shapes can be used to recognize either stationary or moving objects. Such a method of recognizing objects is described, for example, in our copending U.S. application Ser. No. 615,442 filed on May 30, 1984 is incorporated herein by way of reference and which is summarized hereinafter.
More specifically this application discloses a TV image processing system based on a bidimensional correlation technique and comprising a TV camera for scanning a field where at least one object whose coordinates are to be detected is present, an analog-to-digital converter circuitry adapted to convert information from the TV camera into a digital signal, a correlator circuitry receiving as its input said digital signal to output a function of correlation of said input signal to a settable reference, a reference weighing circuitry couple to the correlator circuitry and cooperating therewith to supply said correlation function, a detector circuitry coupled to the output of the correlator circuitry and adapted to detect that a preset threshold has been exceeded in the correlation function and a computer for processing the correlation function.
Thus, as it should be apparent, this system, and in particular its correlator is constructed by a lot of electronic components which process, in real time, the television image. The number of these electronic components, in particular, increases in proportion to the size of the object to be recognized. As a consequence, when large objects are to be recognized, the complexity and cost of the correlator becomes considerable.